wip: state machine updates for tx replay

[hstove]

• Closes Tx Replay: Signer detects forks and updates state machine with replay transactions #5968

This PR implements:

• Detecting forks in the signer state machine
• Updating the tenure fork info API to include dropped blocks, which can be used to construct the tx replay set

This builds on top of #5994

[hstove]

Current state of this PR:

• tx_replay_set, an Option<Vec<StacksTransaction>>, is added the SignerStateMachine
• signer_state detects a bitcoin fork in bitcoin_block_arrival and fetches dropped blocks
• The "fork info" API is updated to included dropped Nakamoto blocks
• The signer updates their local signer state machine with the dropped tx's from this API
• A new integration test triggers a Bitcoin fork and asserts that the state machine has the right tx replay set

[jferrant]

I know this is a WIP so sorry about being nit picky already on eit, but I would make this into a sep function such as handle_bitcoin_fork or extract_replay_transactions as bitcoin_block_arrival is getting a bit long/hard to follow.

[jferrant]

If no sortition occurred, this could be none, right? Does that mean we should just break from this loop?

[hstove]

Hmm, yeah, looking at the API now, it does seem like this will be None if no sortition occurred, and we don't actually want to break from the loop in that case. I'll have to re-think this a bit.